The invention relates to coating apparatus having a tank connected to a high-vacuum pumping system, in which a substrate table is disposed on a rotatably mounted shaft which is introduced through a wall of the tank. The shaft has axial passages through which the supply lines for substrate table are brought out of the tank.
Vacuum coating apparatus of the above kind are known and commonly used as cathode sputtering apparatus. Since a high vacuum must prevail in the tank of such a coating apparatus and the sealing of the rotatable shaft of the substrate table becomes more difficult and less reliable with increasing shaft diameter, it is beneficial to keep the diameter of the shaft as small as possible. However, keeping the shaft diameter small is difficult because in today's apparatus more conduits than formerly have to be brought from the outside through the shaft to the substrate table. The conduits carry water lines for cooling the substrate table, electrical conductors for its heater, conductors for various temperature measuring sensors, or even high-frequency power feeders. Since not only these conduits must be carried in the shaft, but also room for the necessary connections must be provided, such conduits necessitate a considerable and undesirable enlargement of the diameter of the shaft.
The invention is based on the problem of improving a vacuum coating apparatus of the kind described above such that the diameter of the opening that is to be sealed in the tank wall through which the shaft passes can be very small so as to minimize leakage at that point.